The effect of sodium intake on the renin response to dopamine in superfused rat renal cortical cells.

In addition to its natriuretic effect in the kidney, dopamine can also stimulate renin release. This study employs an in vitro system to examine the relationship between sodium intake and dopamine-induced renin release. Enzymically dispersed renal cortical cells obtained from rats on low, normal and high sodium diets were superfused at 37 degrees C with Krebs buffer [0.2% glucose, 0.2% bovine serum albumin (BSA)]. Dopamine was given as 10-min infusions and renin activity was measured in the superfusate as angiotensin I generated following incubation of samples with excess nephrectomized sheep renin substrate. Rats on a low sodium diet showed a higher basal cellular renin release and an enhanced renin response to dopamine (10(-7), 10(-6) mol/l) compared with the normal sodium diet group. Rats on a high sodium diet, in contrast, showed a lower cellular renin release and a decreased sensitivity to dopamine (10(-7), 10(-6) mol/l) compared with the normal sodium diet group. These results demonstrate that the renin response to dopamine is dependent upon sodium intake.